1 2 3 42 4 6X X X NCOS 1 ... ( )X       O X .

3) - TOÁN A3 C3 HUFI EXAM CHUONG 1 A3DH
Toán TOÁN A3 C3 HUFI EXAM CHUONG 1 A3DH

3)

1 2 3 4

2 4 6

x x x n

cos 1 ... ( )

x       O x .